Knife-edge aligner



March 30, 1954 A. R. s'PEARE KNIFE-EDGE ALIGNER Filed Feb. 13. 1953 Fig. 7

JNVENTOR. ALBERT R. spi-:ARE

Fig. 6yk

ATTORNEYS Patented Mar. 30, 1954 UNITED STATE 6 Claims.

In sharpening knives in accordance with conventional practices the beveled edges are subjected to the abrasive action of a stone or grinding Wheel until substantially symmetrical convergeht beveled surfaces are produced, which in the case of household knives usually dene an angle of the order of 40 (included angle). Although the ground surfaces appear from a megascopic examination to be perfectly smooth, yet a microscopic examination shows the cutting edge and adjacent beveled faces to be relatively rough and uneven, being made up of minute ridges and hollows at right angles to the cutting edge. It has been found that such microscopic roughness is a limiting factor in the sharpness of a knife edge.

It has also been found that if the freshly ground surfaces are properly stropped or aligned, the microscopic roughness is reduced to a minimum and the cutting edge is improved by being made thinner and straighter. However, thev proper stropping of a knife requires a skill possessed by very few and Where a person not having the requisite skill attempts to strop a knife, more harm than good is apt to result.

Numerous attempts have heretofore been made to provide devices which in the hands of a relatively unskilled person will effectively strop a sharpened knife, but in most such attempts a spherical sector or the like convex surface is rel lied on to achieve the stropping action. However, unless the beveled surfaces of the knife have been ground to conform to the convexity of the strop, then the stropping operation has little or no effect. If on the other hand, the strop tends to scrape or abrade the ground surfaces, it is likewise ineffective to lproduce an even, smooth surface.

The principal object of the present invention is to provide a strop or knife-edge aligner which may be effectively used by an unskilled person without encountering the aforementioned diiculties.

Further objects relate to features of construction and will be apparent from a consideration of the following disclosure and accompanying drawings, wherein:

Fig. 1 is a top plan view of one form of edge aligner constructed in accordance with the present invention;

Fig. 2 is a side elevation of the edge aligner shown in Fig. `1;

Fig. 3 is a section on the line 3--3 of Fig. 2;

Fig. 4 .is an enlarged `detail Villustrating the action of the edge aligner herein shown;

Fig. 5 is a side elevation of a modified form of .Lis

2 edge aligner constructed in accordance present invention;

Fig. 6 is a top plan View of the edge vraligner' shown in Fig. 5; and

Fig. 7 is an end elevation of the edge aligner shown in Fig. 5.

An edge aligner constructed in accordance with the present invention comprises a base of any suitable rigid material such as hard Wood, plastic, metal or the like, and mounted on the base is a plurality of similarly shaped, edge-aligning elements rotatable horizontally von spaced parallel axes. The aligning elements 'consist essentially of substantially Afrnstoconical members disposed so that the smaller end of the 'rst is adjacent to the periphery of the base of the second and the periphery of the base of the latter is adjacent to the smaller end of the former, etc., the frusto-conical surfaces of these members being closely spaced and defining a symmetrical V- shaped groove when viewed from a point in a plane defined by and at right angles to the axes of rotation of the members.

The angle of the V-shaped groove is greater than the included angle of the knife to be honed, preferably by an amount of the order of 10 to'20. For example, if the included angle of a knife to be sharpened is 40 to 45, then the V-shaped groove should be 55 to 60, i. e., approximately 15 greater, which produces a very small contact area between the knife edge and frusto-conical surface. Hence, a few pounds pressure on the knife during the edge aligning operation produces a pressure of several hundred pounds p. s. i. at the line of contact with the algning elements. rEhe frusto-conical surfaces of the aligning elements may be of any material having a hardness substantially greater than that of the knife blade and to this end a hardened steel or alloy surface is satisfactory.

Guiding means are cooperatively positioned with respect to the aligning elements so that the latter may simultaneously operate on the narrow convergent surfaces defining the cutting edge without injury to the latter. To this end the guiding means may comprise spaced parallel elements mounted above the aligning elements; or such means may comprise additional aligning members similar to the first and second members and rotatably mounted on the base in the same relation to the second as that of the first member. In either case the knife is supported .so that it may be drawn along a path which bisects the V-shaped groove and extends at right 'angles to the axes of rotation of the aligning members.

with the The aligning operation simply requires the knife to be drawn back and forth along the aforesaid path as a slight pressure is applied thereto. As the knife moves the cones are rotated and, in effect, calenders and burnishes a narrow convergent area at the cutting edge, without injury to the latter, so as to produce an attenuated and smoother cutting edge.

Referring to the accompanying drawings, particularly to Figs. 1 to 3, the base I comprises a pair of plastic blocks 2 and 3 secured together by screws 4 and 5, and formed with centrally disposed recesses dening a chamber 6 and longitudinally extending recesses along their opposed upper side faces which define a slot 8 communicating with the central chamber 6. The blocks are drilled transversely to provide spaced, parallel bearings IG and I2 which receive shafts or pintles I4 and I 6, and one end of each bearing is threaded to receive an Allen set screw I8 which holds a ball bearing against one end of the shaft, thus providing a thrust bearing permitting a slight axial play.

Mounted on the shafts I4 and I5 are frustoconical aligning elements 22 and 24 which are so disposed that the smaller end of one is adjacent the periphery of the base of the other with their frusto-conical surfaces in closely spaced relation (Fig. 1) and defining a V-shaped groove 25 (Figs. 3 and 4) vertically aligned with slot 8. The angle of groove 25 is preferably approximately 60 which is about 15 greater than the included angle of the knife K, the cutting edge of which is to be aligned, illustrated in Fig. 4.

In order to hold the knife K properly positioned the width of the slot 3 is slightly greater than the thickness of the blade so that the walls of the slot provide spaced guiding members engageable with the knife as it is drawn back and forth. When the knife K is inserted in slot 8 the narrow convergent areas defining its cutting edge contact the aligning elements 22 and 24, as illustrated in Fig. 4, and by the application of slight pressure as the knife is being drawn back and Vforth a proper edge aligning is effected without danger of injury to the cutting edge.

The embodiment shown in Figs. 5 to '7 is in principle the same as that of Figs. l to 4 and the same or similar reference characters are applied tc corresponding parts. In this embodiment the guiding means comprises a third frusto-conical member rotatably mounted in bearings carried by the block Si in the same manner as the aligning elements 22 and 2t, the

element 3B having the same corresponding relation to the element 22 as does the element 212. Since the three elements are aligned they automatically center the knife. In all other particulars, the construction and operation is as above described.

Y While I have shown and described two desirable embodiments of the invention, it is to be understood that this disclosure is for the purpose of illustration and that various changes and modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

l. A knife-edge aligner comprising a base, at least two similarly shaped, aligning elements mounted on said base sc as to rotate on spaced parallel axes, said aligning elements consisting essentially of substantially frusto-conical members disposed so that the smaller end of the first member is adjacent to the periphery of the base of the second member and the periphery of the base of the latter is adjacent to the smaller end of the former, the frusto-conical surfaces of the members being in closely spaced relation defining a symmetrical, J -shaped groove when viewed from a point in a plane defined by and at right angles to said axes, the angle of said V-shaped groeve being greater than the included angle of a knife to be treated, and means cooperatively positioned with respect to said aligning elements to guide a knife along a path at right angles to said axes.

2. A knife-edge aligner as set forth in claim 1, wherein the guiding means comprises a pair of spaced parallel members mounted on said base above said aligning elements so as to engage the opposite faces of a knife.

3. A knife-edge aligner as set forth in claim 1, wherein the guiding means comprises a third aligning member similar to the other members and rotatably mounted on said base in the same relation to the second member as that of the first member.

4. A knife-edge aligner as set forth in claim 1, wherein each of said aligning elements has a hardened metallic frusto-conical surface.

A knife-edge aligner comprising a blockshaped base having a central chamber and an elongate slot extending from one end of said base to the other and communicating with said chamber, the width of the slot being slightly greater than the thickness of the blade of a knife to be treated, a pair of similarly shaped aligning elements mounted within said chamber so as to rotate on spaced, parallel axes, said aligning elements consisting essentially of substantially frusto-conical members disposed so that the smaller end of the first member is adjacent to the periphery of the base of the second member and the periphery of the base of the latter is adjacent to the smaller end of the former, the frusto-conical surfaces of the members being in closely spaced relation and defining a symmetrical V-shaped groove when viewed from one end of said slot, the angle of said V-shaped groove being greater than theinoluded angle of a knife to be treated, said V-shaped groove being in alignment with said slot so that the wall defining said slot provides a guiding means engageable with the opposite faces of the knife being treated.

6. A knife-edge aligner comprising a base, and three similarly shaped aligning elements mounted on said base so as to rotate on spaced, parallel axes, said aligning elements consisting essentially of substantially frusto-conical members disposed so that the smaller end of the second member is between the peripheries of the bases of the iirstY and third members and the periphery of the base of the second member is between the smaller ends of the first and third members.

ALBERT R. SPEARE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,458,938 Heyman June 19, 1923 2,451,860 Munno Oct. 19, 1948 FOREIGN PATENTS Number Country Date 2,603 Great Britain Sept. 14, 1867 

